Polyesters from 2,6-naphthalenedicarboxylic acid and tris(2-hydroxyethyl)isocyanurate

ABSTRACT

1. A COATING-FORMING POLYESTER CONSISTING ESSENTIALLY OF UNITS DERIVED FROM (A) AN AROMATIC 2,6 - NAPHTHALENEDICARBOXYLIC ACID COMPONENT CONSISTING OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF 2,6-NAPHTHALENE-DICARBOXYLIC ACID AND THE LOWER ALKYL ESTERS AND HALIDES THEREOF AND 0-10 MOL PERCENT, BASED ON SAID MEMBER, OF OTHER DICARBOXYLIC ACIDS OR DERIVATIVES THEREOF SELECTED FROM THE GROUP CONSISTING OF THE AROMATIC DIBASIC ACIDS OTHER THAN 2,6 - NAPHTHALENEDICARBOXYLIC ACID, THE LOWER ALKYL ESTERS AND HALIDES OF SAID AROMATIC DIBASIC ACIDS, AND THE ALIPHATIC DIBASIC ACIDS AND THE LOWER ALKYL ESTERS AND HALIDES THEREOF; AND (B) AN ALCOHOL COMPONENT CONSISTING OF TRIS(2-HYDROXYETHYL)ISOCYANURATE AND OTHER DI- OR TRIHYDRIC ALCOHOLS, THE LATTER POLYHYDRIC ALCOHOLS BEING CONTAINED IN AN AMOUNT OF 0-60 MOL PERCENT OF THE TOTAL OF SAID ISOCYANURTE AND OTHER POLYHYDRIC ALCOHOLS; WITH THE PROVISO THAT SAID AROMATIC 2,6-NAPHTHALENEDICARBOXYLIC ACID COMPONENT (A) ACCOUNTS FOR 40-50 EQUIVALENT PERCENT OF THE WHOLE POLYESTER.

United States Patent POLYESTERS FROM 2,6 NAPHTHALENEDICAR- BOXYLIC ACID AND TRlS(2-HYDROXYETHYL) ISOCYANURATE Yasukuni Nakatsuji, Tamaki Kauai, Hiroshi Noda, and Sadayoshi Miura, Sagamihara, and Hideaki Suzuki, gokyo, Japan, assignors to Teijin Limited, Osaka,

apan No Drawing. Filed Jan. 16, 1973, Ser. No. 324,085

Int. Cl. C08g 17/08 US. Cl. 260-75 N 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a coating-forming polyester composition that demonstrates outstandingly improved properties for forming electric insulating coatings, such as for the formation of insulation for electric wires, in that it conjointly possesses in particular such improved properties as heat-shock resistance, resistance to heatsoftening and after-heating windability.

In concomitance with the development of electrical appliances there has arisen a demand for overcoming the degradation at elevated temperatures of the resins used for forming electric insulating coatings. In consequence, the polyester resins or modified polyester resins, which excel in such properties as thermal resistance and mechanical strength are attracting attention. The present invention concerns a coating-forming polyester composition that demonstrates outstandingly improved properties for this purpose.

More specifically, the invention relates to a coatingiorming polyester composition comprising units derived rom (A) an aromatic 2,6-naphthalenedicarboxylic acid component consisting of a member selected from the group consisting of 2,6-naphthalenedicarboxylic acid and the lower alkyl esters and halides thereof and 0l0 mol percent based on said member, of other dicarboxylic acids or derivatives thereof selected from the group consisting of the aromatic dibasic acids other than 2,6- naphthalenedicarboxylic acid, the lower alkyl esters and halides of said aromatic dibasic acids, and the aliphatic dibasic acids and the lower alkyl esters and halides thereof; and

(B) an alcohol component consisting of tris(2-hydroxyethyl)isocyanurate and other dior trihydric alcohols, the latter polyhydric alcohols being contained in an amount of 0-60 mol percent of the total of said isocyanurate and other polyhydric alcohol; with the provision that the foregoing aromatic 2,6-naphthalenedicarboxylic acid component (A) accounts for 40-50 equivalent percent of the whole composition.

A number of polyester compositions are known in which tris(2-hydroxyethyl)isocyanurate (for brevity to be hereinafter referred to, at times, as THEIC) has been used for a part of all of the alcohol component. For

3,849,382 Patented Nov. 19, 1974 ice instance, in German Pat. No. 1,251,528 (published Oct. 5, 1967) there is a disclosure concerning a process for the preparation of polyesters including a polyester derived from THEIC and 1,4-naphthalenedicarboxylic acid. However, there is no mention at all in this patent of a polyester derived from THEIC and 2,6-naphthalenedicarboxylic acid. Neither is there any mention of the resulting polyester being used for forming an electric insulating coating. On the other hand, in US. Pat. 3,342,780 (patented Sept. 19, 1967) there is disclosed a reaction product of a dibasic polycarboxylic acid and THEIC, which is used for forming electric insulating coatings. While in this patent there is mentioned the use of terephthalic or isophthalic acid and the acyl halides or lower dialkyl esters thereof as the dibasic polycarboxylic acid, no mention is made at all of the use of naphthalene-dicarboxylic acids and the acyl halides or lower dialkylesters thereof. Further, in US. Pat. 3,374,114 (patented Mar. 19, 1968) there is disclosed the utilization as a resin for forming insulating coatings of a polyester derived from the straight, branched or cyclic glycols and 2,6-, 2,7- and/or 1,S-naphthalenedicarboxylic acid in which a member selected from the group consisting of terephthalic or isophthalic acid and the lower alkyl esters thereof may be contained in an amount as high as 70 mol percent. This patent however makes no mention at all of the use of the THEIC component.

We found that a coating-forming polyester composition not mentioned in any of the foregoing proposals could be provided by carrying out the esterification or trans esterification reaction of 40-50 equivalent percent of the aforesaid aromatic 2,6-naphthalenedicarboxylic acid component (A) and 6050 equivalent percent of the alcohol component (B) at ISO-300 C. in the presence of an esterification or transesterification catalyst, and that the so obtained composition conjointly possessed in an outstandingly improved state the various properties required for forming an electric insulating coating.

It is therefore an object of the present invention to provide a coating-forming polyester composition which demonstrates outstandingly improved properties for forming electric insulating coatings as compared with the conventional proposals, and to a process for preparing such a composition.

Other objects and advantages of the present invention will become apparent from the following description.

In accordance with the present invention, 40-50 equivalent percent of an aromatic 2,6-naphthalenedicarboxylic acid component (A) consisting of a member selected from the group consisting of 2,6-naphthalenedicarboxylic acid and the lower alkyl esters, preferably the C -C alkyl esters, and the halides thereof, and 010 mol percent, preferably 05 mol percent, based on the foregoing member, of other dicarboxylic acids or derivatives thereof selected from the group consisting of the aromatic dibasic acids other than 2,6-naphthalenedicarboxylic acid, the lower alkyl esters and halides of said aromatic dibasic acids, and the aliphatic dibasic acids and the lower alkyl esters and halides thereof; and 60-50 equivalent percent of an alcohol component (B) consisting of tris(Z-hydroxyethyl)isocyanurate and other dior trihydric alphatic alcohols, wherein the latter polyhydric alcohols are contained in an amount of 0-60 mol percent, based on the total of said isocyanurate and other polyhydric alcohols, are submitted to an esterification or transesterification reaction at ISO-300 C. in the presence of an esterification or transesterification catalyst.

As the other dicarboxylic acids or derivatives thereof that the aromatic 2,6-naphthalenedicarboxylic acid component (A) may contain, included are such, for example, as the aliphatic dibasic acids and the lower alkyl esters or halides of said dibasic acids selected from the group consisting of adipic acid, succinic acid, maleic acid and sebacic acid, the C -C alkyl esters of said acids and the halides, preferably the chlorides and bromides of said acids, which may be used either singly or in combination of two or more thereof. Preferred however is the use of the aromatic dibasic acids and the lower alkyl esters or halides of said dibasic acids selected from the group consisting of the naphthalenedicarboxylic acids other than 2,6-naphthalenedicarboxylic acid, the other isomers, terephthalic acid and isophthalic acid, and the C -C alkyl esters of said acids and the halides, preferably the chlorides and bromides, of said acids, which may be used either singly or in combinations of two or more thereof.

Of these other dicarboxylic acids or derivatives thereof, preferred are the dibasic acids or their lower alkyl esters.

As the other dior trihydric aliphatic alcohol that may be contained in the alcohol component (B) in addition to the tris(2-hydroxyethyl)isocyanurate, mention can be made of a member selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, glycerin, pentaerythritol and trimethylolpropane. Of these, preferred are the dihydric aliphatic alcohols, ethylene glycol and propylene glycol being especially preferred.

In the invention process the aromatic 2,6-naphthalenedicarboxylic acid component (A) is used in an amount of 40-50 equivalent percent to the 60-50 equivalent percent of the alcohol component (B) consisting of THEIC or THEIC containing other polyhydric alcohols. When the acid component (A) is less than 40 equivalent percent, the thermal resistance and mechanical properties of the polyester composition decline. n the other hand, when the amount of the acid component (A) exceeds 50 equivalent percent, this also is objectionable, since the mechanical properties of the polyester composition sufier.

Further, when the other dicarboxylic acids or derivatives thereof, which may be contained in an amount of 0-10 mol percent, preferably 0-5 mol percent, based on the member selected from the group consisting of 2,6-naphthalenedicarboxylic acid, and the lower alkyl esters and halides thereof, exceed mol percent, the thermal resistance of the polyester coating obtained by curing becomes poor.

Further, when the amount of the other dior trihydric aliphatic alcohols which may be contained in an amount of 0-60 mol percent based on the total of THEIC and the other polyhydric alcohol, exceeds 60 mol percent, not only does the thermal resistance of the coating decline but also turbidity is set up in the composition when it is made into a varnish resulting in loss of stability.

The coating-forming polyester composition of this invention can be obtained by the conventional esterification or transesterification reaction, namely by reacting the aromatic 2,G-naphthalenedicarboxylic acid component (A) and the alcohol component (B) at a temperature of ISO-300 C. in the presence of an esterification or transesterification catalyst. Known esterification or transesterification catalysts can be used, including metal oxides such as litharge, lead oxide and lithium oxide and metal salts such as lithium acetate and zinc acetate. While the amount of catalyst used can be suitably chosen in accordance with the class of the reactants, the class of catalyst, the molar ratio of the component (A) to component (B) and the reaction temperature, it is usually 0.1-0.5 percent by weight based on the total weight of the acid component charged. The reaction procedure is well known and is carried out in the following manner. The components (A) and (B) and catalyst are added in prescriptive amounts and, after the mixture is deaired, it is heated with stirring in a stream of an inert gas. First, water and alcohol are distilled off gradually at 200 C. and the temperature is raised to 230 C. by the time the water and alcohol removed amount to of theory. The reaction is brought to conclusion finally at 250 C. before gelation takes place. The reaction is stopped by cooling or by the addition to the reaction system of a cresol-toluene type solution. The addition of the cresol-toluene type solution is to be especially preferred.

The coating-forming polyester composition of this invention can be used in the form of an insulating varnish in which have been incorporated a curing agent and an aromatic organic solvent which dissolves said polyester. In this case, it is possible to add such additives as a colorant such as a dye or a pigment such as TiO a stabilizer such as hindered phenol type antioxidant and lauryl tin, extenders such as calcium carbonate and aluminum silicate, and inorganic fillers such as mica powder, talc and clays. As examples of the foregoing aromatic organic solvents, mention can be made of benzene, toluol, phenol, cresol and mineral spirit. The foregoing curing agents include tetraalkyl titanates, preferably the tetraalkyl titanates in which the alkyl group is of 1-5 carbon atoms, metal salts, preferably the Co and Zn salts, of naphthenic acid, and blocked isocyanates. These blocked isocyanates, mention can be made of those obtained by blocking with 3 mols of phenol an isocyanate type compound obtained from trimethylolpropane and 3 mols of toluene diisocyanate.

According to a preferred embodiment of the invention, the coating-forming polyester composition provided demonstrates exceptionally excellent performances in the physical properties hereinafter described, such as a resistance to heat-softening of above 470 C., a heat-shock resistance of above 200 C. and an after-heating Windability of 1 time.

In the present invention the resistance to heat-softening, the heat-shock resistance, and the after-heating windability are physical properties, which are determined by the following tests.

(a) Resistance to heat-softening To 1000 grams of a m-cresol solution of a polyester composition whose solids content is 50% by weight are added 820 grams of m-cresol and 180 grams of mineral spirit to prepare a varnish whose resinous solids content is 25% by weight, to which is added 20 grams of tetraisopropyl titanate as the curing agent to prepare the sample varnish.

The varnish is baked to a coating thickness of 40-60 microns onto one side of a rectangular copper plate having a length of 7.5 cm., a width of 6.0 cm. and thickness of 300 microns. This sample is placed on top of a load receiving block having an electrically conductive metallic plate surface in such a manner that the surface with the varnish baked on comes into contact with the surface of the load receiving block. A S-kg. load is then placed atop the varnished copper plate, and an alternating current of volts is applied across the load receiving block and the sample copper plate to raise the temperature of the surrounding atmosphere. As the temperature rises, the coating of the copperplate softens and shorting of the circuit takes place. The temperature C.) at which the short circuit takes place is used to indicate the resistance to heat-softening.

(b) Heat-shock resistance The same varnish as that used in (a), above, is used.

A copper wire of 1-mm. diameter is applied and baked with this varnish for seven times under the conditions of a furnace temperature of 350 C. and a linear velocity of 8.0 meters per minute. Thus is prepared an enameled electric wire having a coating thickness of 35 microns. A core rod of the same diameter as the enameled wire is used, and coils are prepared by winding the wire about the core rod for 20 times. A total of 12 coils, three for each temperature at which measurement is to be made, are prepared. These coils are exposed for one hour at the several 6 temperatures of 150, 175, 200 and 225 C. After ex- Widmer spiral, a thermometer, a nitrogen inlet line and posure to the foregoing temperatures, the coils are exa stirrer. There was also provided a receiver for determinamined for the presence of cracks, using a magnifying ing the water content and a condenser at the top of the glass. Even the presence of a single crack disqualifies the spiral. Next, 13 grams of mineral spirit, 7 grams of xylene coil. The maximum temperature C.) at which all coils 5 and as catalyst 0.085 grams of litharge were added and, were free of cracks is used to indicate the heat-shock after deairing, the mixture was heated at 160-175 C. to resistance. distill off the methanol gradually. The water of the jacket (c) After-heating windability was then removed and the temperature was raised and,

. fter distilling oif the mineral s irit x lene and methanol An enameled wire re ared as in b is ex osed for a a P y 6 hours in a heated ZIlLIlfOSPhGIC of 552) C. loils are at 200-210. the Splral was removed and the rqcewer then prepared from this wire by winding it 20 times for deltlermining the water content was connecteddirectly about core rods having diameters 1 2 5 and 10 times with t e flask, after which the reaction was continued at the wire diameter. The presence of cracks is examined as g th till 1 d h in (b), and the smallest diameter at which the coils were en 6 1S Ion was comp etc t e ,flask free of cracks is used to indicate the after-heating windcooled and by addmg m'cresol the resultmg resm was abilim Thus, the smaller this value the better is the wire solved to obtain a resinous solution whose solids content with respect to its ft h ti Windabi1ity was 50% by weight. The previously-described tests were h f ll i examples, along with control experi. conducted using the resulting resinous solution whose ments, will be given to illustrate several modes of praccontent of Polyester Solids was 50% y Weight. The ticing the process of the present invention. breviations used in the table have the following meanings.

EXAMPLES AND CONTROL DMN-dimethyl ester of naphthalenedicarboxylic acid.

The dicarboxylic acid components (used in the form DMT-dilmethyl ester of tefephthalic acidof dimethyl esters) and alcohol components indicated in DMITdimethY1 ester of isophthalic acidthe hereinafter given Tables 1 and 2 were used in the y y equivalent percent as indicated therein. These components PG-propylene glycol. were placed in a SOO-cc. 4-necked flask equipped with a THEIC-tris(2-hydroxyethyl)isocyanurate.

TABLE 1 Properties Alcohol component (B) Resist- Heat After THEIC 1 E G 2 P G 2 ance resistant heating Dicarboxylic acid component (A) (equivalent percent) (equiv- (mol (mol to heatimpact windalent perpersoitenin strength ability Number 2.6-DMN 2.7-DMN 1.6-DMN 1.5-DMN 1.4-DMN DMT DMIT percent) cent) cent) C. C. (times) Example 1 40 525 225 1 Control 1-.- 520 175 1 Control 2-; 511 175 2 Control3 40 60 (State of condensation poor; could not be withdrawn in a varnish state; so sample could not be prepared.) Control 4- .r 501 Control 5. 489 Control 6- 489 175 2 Control 7. 480 175 2 Example 2. 540 225 1 Example 3, 522 225 1 Control 8..... 547 175 1 Control 9 50 511 175 2 Control 10. 50 (State of condensation poor; could not be withdrawn in a varnish state, so sample could not be prepared.) Control 11-.;.--;.-::-:.:-..;;..;.;.;....-:;-...:-;: 50 507 Control 12- 1 492 l) Control 13. 492 175 2 Control 14.. 433 175 Example 4.... 40 517 200 1 Control 15. 30 507 175 Example 5.... 45 519 200 1 Example 6....- 50 514 200 1 Control 16. 60 521 175 2 Example 7...- 45 519 225 1 Control 17. 45 487 Control 18. r 45 487 175 1 Control 19. 45 452 1 Example 8.. 45 25 511 200 1 Control 20. 45 25 510 150 1 Control 21 45 (55) 25 (State oi condensation poor; not possible to obtain in varnish form.) Control 22 45 (55) 25 500 Control 23. 4.5 3 55 (Cannot be obtained as varnish by the same polymerization method.)

1 The figure in the parentheses indicates the equivalent percent of the total of THEIC and E G or PG contained in the polyester composition. 9 Mol percent based on the total of THEIC and EG or P G.

3 Equivalent percent contained in polyester component.

4 No capacity for forming coating; comes oil in a powdery state.

5 N 0 capacity for forming coating; measurement impossible.

Measurement impossible.

TABLE 2 Pro ertics Dicarboxylie acid component (A) Alcohol component (B) p Resist- Heat- After- 2.6-DM N DMI DMI'I THEIC E G P G ance resistant heating (equiv- 2. 7-DMN 1.6-DMN 1 -DMN 1.4-DMN (mol (mol (equiv- (mol (mol to heatimpact windalent (mol (mol (mol (mol erperalent perpersoltenin strength ability Number percent) percent) percent) percent)* percent) cent) cent) percent) cent) cent) 0E 0.) (times) Example 9.... (55) 520 225 1 Example 10..- (55) 522 225 1 Control 24.... (70) (Solution become turbid; could not be obtained in varnish form, so sample could not be prepared.)

Example 11... (53) 498 200 Control 25.... (53) 30 (State of condensation poor; could not be withdrawn in a varnish state; so sample could not be prepared.)

Example 12... (57) 30 462 200 1 Control 26.... (57) 30 (State of condensation poor;

'Mol percent on component (A).

could not be withdrawn in a varnish state; so sample could not be prepared.)

"M01 percent based on the total of 'IHEIC and EG or PG and the values in the parentheses of the THEIO column indicate in equivalent percent the content of said total in the polyester component.

We claim:

1. A coating-forming polyester consisting essentially of units derived from (A) an aromatic 2,6 naphthalenedicarboxylic acid component consisting of a member selected from the group Consisting of 2,6-naphthalene-dicarboxylic acid and the lower alkyl esters and halides thereof and 0-10 mol percent, based on said member, of other dicarboxylic acids or derivatives thereof selected from the group consisting of the aromatic dibasic acids other than 2,6 naphthalenedicarboxylic acid, the lower alkyl esters and halides of said aromatic dibasic acids, and the aliphatic dibasic acids and the lower alkyl esters and halides thereof; and

(B) an alcohol component consisting of tris(2-hydroxyethyl)isocyanurate and other dior trihydric alcohols, the latter polyhydrie alcohols being contained in an amount of 0-60 mol percent of the total of said isocyanurate and other polyhydric alcohols; with the proviso that said aromatic 2,6-naphthalenedicarboxylic acid component (A) accounts for 40-50 equivalent percent of the whole polyester.

2. A polyester according to claim 1 wherein said other dicarboxylic acid or derivative thereof is a member selected from the group consisting of naphthalenedicarboxylic acids other than 2,6-naphthalenedicarboxylic acid, ter- UNITED STATES PATENTS 6/1969 Burdick et al. 260 9/1967 Meyer et al. 260-75 OTHER REFERENCES Hill: Fibres from Synthetic Polymers, Elsevier, New York, 1953, p. 156.

Hill et al.: J. Polym. Sci. 3, 620 and 623 (al948).

I MELVIN GOEDSTEIN, Primary Examiner US. Cl. X.R.

117230, 132 B; 260-33.4 P, 33.6 R 

1. A COATING-FORMING POLYESTER CONSISTING ESSENTIALLY OF UNITS DERIVED FROM (A) AN AROMATIC 2,6 - NAPHTHALENEDICARBOXYLIC ACID COMPONENT CONSISTING OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF 2,6-NAPHTHALENE-DICARBOXYLIC ACID AND THE LOWER ALKYL ESTERS AND HALIDES THEREOF AND 0-10 MOL PERCENT, BASED ON SAID MEMBER, OF OTHER DICARBOXYLIC ACIDS OR DERIVATIVES THEREOF SELECTED FROM THE GROUP CONSISTING OF THE AROMATIC DIBASIC ACIDS OTHER THAN 2,6 - NAPHTHALENEDICARBOXYLIC ACID, THE LOWER ALKYL ESTERS AND HALIDES OF SAID AROMATIC DIBASIC ACIDS, AND THE ALIPHATIC DIBASIC ACIDS AND THE LOWER ALKYL ESTERS AND HALIDES THEREOF; AND (B) AN ALCOHOL COMPONENT CONSISTING OF TRIS(2-HYDROXYETHYL)ISOCYANURATE AND OTHER DI- OR TRIHYDRIC ALCOHOLS, THE LATTER POLYHYDRIC ALCOHOLS BEING CONTAINED IN AN AMOUNT OF 0-60 MOL PERCENT OF THE TOTAL OF SAID ISOCYANURTE AND OTHER POLYHYDRIC ALCOHOLS; WITH THE PROVISO THAT SAID AROMATIC 2,6-NAPHTHALENEDICARBOXYLIC ACID COMPONENT (A) ACCOUNTS FOR 40-50 EQUIVALENT PERCENT OF THE WHOLE POLYESTER. 